Mobile communication devices of recent years include some models that employ a diversity scheme in order to secure constant communication quality when moving. Here, the diversity scheme includes two schemes: a switching scheme and a composite scheme. The switching scheme is a scheme for maintaining reception quality by selecting a receiver having higher communication quality between two branches (two antennas, and in some cases, two receivers). Moreover, the composite scheme is a scheme for enhancing reception quality by synthesizing inputs of two branches.
Here, in the composite scheme, although reception quality is higher than that of the switching scheme, there is a drawback that the power consumption is increased. In order to solve this drawback, various kinds of techniques have been proposed (for example, see Patent Document 1).
Patent Document 1 discloses a technique, in which only a first branch (antenna) is firstly turned on to perform communication (switching scheme), and then, based on communication quality of a receiver during communication, a second branch (antenna) is turned on to perform communication by using both antennas (composite scheme). In addition, in the technique disclosed in Patent Document 1, while both antennas are being used to perform communication, based on communication quality of the second antenna, communication is performed by turning off the first antenna (switching scheme). In this way, a technique has been proposed, in which both the composite scheme and the switching scheme are used depending on the reception situation, thereby improving the power consumption.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2007-129630